A narrative review of SARS-CoV-2 pathogenesis, transmission, and clinical manifestations

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a major global concern. As of writing this manuscript, there are over 224 million cases diagnosed with the coronavirus disease 2019 (COVID-19) and 4.5 million recorded deaths by the disease. Objectives: This review article investigates studies conducted on SARS-CoV-2 pathogenesis, transmission, and different clinical manifestations of COVID-19. Methods: An extensive online search was conducted on PubMed, and Google Scholar databases. Some keywords including “SARS-CoV-2”, “COVID-19”, “virology”, “mechanism of action”, “transmission”, “clinical manifestations”, “laboratory findings”, “comorbidities”, and their combinations were used for this review. Results: The SARS-CoV-2 spike glycoprotein recognizes the human angiotensin-converting enzyme 2 receptor, and through that the virus can enter its host cell. The virus is mainly transmitted via respiratory and/or airborne droplets. Severity of the COVID-19 clinical manifestations relies on the associated comorbidities and/or old age, which range from little-to-no symptoms to severe and critical conditions. Fever, loss of appetite and/or smell, fatigue, and dry cough are among the most reported symptoms. Underlying conditions may lead to severe or critical stages of COVID-19. Conclusion: The SARS-CoV-2 nucleocapsid and RBD could be two potential targets for future vaccines and drugs. It appears the virus is adapting to each region’s specific environment and, therefore, new endemic variants are forming.